It is necessary to know the behaviour of the fluids contained in a reservoir rock to be able to estimate the recoverable oil and gas amounts, and to determine the separation conditions allowing a maximum proportion of liquid products to be obtained. The behaviour of hydrocarbon mixtures can be studied in the laboratory in steel cells wherein it is possible to vary the volume provided for the fluid by mercury intrusion or retraction by means of a positive-displacement mercury pump connected thereto. Other pressurization and volume variation mechanisms are used, for example by means of a motorized piston interior to the cell. The temperature of the cell is controlled and portholes made of a transparent material allow to observe the first fog formation (dew point) and the condensed volumes. The study can be performed with a constant or a variable mass.
The cells that are currently known involve drawbacks and limitations, notably as regards the low volume of fluid tested because of the technically possible small cell size, the low-performance visualization means, the measuring means linked with detection of the gas/liquid interface position, etc.
Document FR-2,856,797 describes a measuring device and method comprising a cell tilting system for measurements on condensate gases or liquids. However, the interface visualization system is not optimal, notably as regards the study of condensate gases.